.jpg) Blanca near peak intensity on June 3 | |
| Meteorological history | |
|---|---|
| Formed | May 31, 2015 |
| Dissipated | June 9, 2015 |
| Category 4 major hurricane | |
| 1-minute sustained (SSHWS/NWS) | |
| Highest winds | 145 mph (230 km/h) |
| Lowest pressure | 936mbar (hPa); 27.64 inHg |
| Overall effects | |
| Fatalities | 4 |
| Damage | $134,000 |
| Areas affected | Western and Northwestern Mexico,Revillagigedo Islands,Southwestern United States |
| IBTrACS /[1] | |
Part of the2015 Pacific hurricane season | |
Hurricane Blanca was the earliest recordedtropical cyclone in the calendar year to makelandfall on theBaja California Peninsula. Forming as the secondnamed storm, hurricane, and major hurricane of theannual hurricane season, the system first developed into atropical depression on May 31. The storm initially struggled to organize due to strongwind shear, but once this abated, the system took advantage of highsea surface temperatures and ample moisture. After becoming atropical storm on June 1, Blancarapidly intensified on June 2–3, becoming a powerfulCategory 4 hurricane on theSaffir–Simpson hurricane wind scale;maximum sustained winds reached 145 mph (230 km/h) at this time. The hurricane's slow motion resulted in tremendousupwelling of cooler water, resulting in a period of weakening. Blanca gradually recovered from this and briefly regained Category 4 status on June 6 as it moved generally northwest toward the Baja California peninsula. Cooler waters and increased shear again prompted weakening on June 7 and the system struckBaja California Sur on June 8 as a weak tropical storm. It quickly degraded to a depression and dissipated early the next day.
Although Blanca remained far fromJalisco, largeswells andrip currents produced by the hurricane claimed four lives. In Northwestern Mexico,watches and warnings were raised prior to the storm's landfall. Blanca caused generally light damage in the region, consisting of downed trees and power lines. Remnant moisture from the system spread across theSouthwestern United States, resulting in several days of scattered thunderstorms.Flash flooding occurred in multiple states, washing out roads and damaging homes, though the overall effects were limited.
Extratropical cyclone, remnant low, tropical disturbance, or monsoon depressionOn May 26, 2015, atropical wave traversed Central America and entered the Eastern Pacific. Little development occurred over the following few days as the system drifted westward.Convective activity finally blossomed on May 30 and following the consolidation of asurface low,[1][2] it was classified as a tropical depression by 12:00 UTC on May 31. At this time, the depression was situated 370 mi (595 km) south-southwest ofAcapulco, Mexico. The system initially drifted northwest along the edge of a weakridge; however, steering currents soon collapsed and left the depression to meander in the same general region for four days.[1] Strong wind shear stemming from the nearbyHurricane Andres precluded intensification of the nascent depression. Other factors, including a moist atmosphere andsea surface temperatures of 86 °F (30 °C) presented favorable conditions for development once the shear relaxed.[2] Formation of acentral dense overcast on June 1 marked the transition into a tropical storm,[3] at which time the system wasassigned the nameBlanca.[1] As shear steadily relaxed, conditions became exceptionally favorable forrapid intensification. Accordingly, theStatistical Hurricane Intensity Prediction Scheme showed a 90 percent chance of winds increasing by 45 mph (75 km/h) in 24 hours, among the highest probabilities seen byNational Hurricane Center (NHC) forecaster Michael Brennan.[4]
The upper-level environment became even more favorable during the overnight of June 1–2 as anticyclonicoutflow developed above Blanca, providing necessary ventilation for intensification.[5] Turning south along an erratic, drifting course,[1] aneye feature developed within the storm's convective mass on June 2.[6] Blanca reached hurricane strength by 18:00 UTC and underwent rapid intensification thereafter.[1] A small, pinhole eye soon appeared on visible and infrared satellite imagery.[7] Reachingmajor hurricane intensity by 12:00 UTC on June 3, Blanca marked the earliest occurrence of a season's second such storm on record.[1] The system featured a small, well-defined eye surrounded by intense convection.[8] Hours later, at 18:00 UTC, the hurricane achieved its estimated peak strength as aCategory 4 on theSaffir–Simpson hurricane wind scale withmaximum sustained winds of 145 mph (230 km/h) and abarometric pressure of 936mbar (hPa; 27.64 inHg).[1] Given continued favorable conditions, forecasters at the NHC predicted Blanca to achieveCategory 5 status—the highest ranking on the scale, indicating winds in excess of 156 mph (251 km/h).[9]
Contrary to forecasts,[9] the still quasi-stationary Blanca soon degraded. The hurricane's persistence over the same location for several days resulted in tremendousupwelling of cooler waters, with temperatures underneath the storm falling from 30 to 21 °C (86 to 70 °F).[10] Compounding the effects of cooler water was aneyewall replacement cycle. This resulted in rapid weakening, with Blanca's winds falling to 90 mph (150 km/h) by 12:00 UTC on June 5.[1] The previously small core of Blanca dramatically expanded to 65 mi (100 km) across,[11] with convection asymmetrically wrapping around it.[12] During this period, a mid-level ridge north of the hurricane moved east and allowed Blanca to acquire a steady northwest track. Re-intensification ensued on June 6 as the hurricane moved away from its cold wake and traversed an area of warmer water.[1]
Throughout June 6, Blanca's convective structure became more symmetric as it completed its eyewall replacement cycle.[1][12] Aided by impressive outflow,[13] the hurricane regained Category 4 status by 12:00 UTC, marking its secondary peak intensity with winds of 130 mph (215 km/h). Soon thereafter, Blanca moved back over cooler waters and began weakening. A turn to the north-northwest also occurred at this time as it rounded a mid-level ridge over Mexico. The hurricane passed roughly 30 mi (45 km) northeast ofSocorro Island on June 7. An automated weather station there recorded sustained winds of 74 mph (119 km/h), with a peak gust of 101 mph (163 km/h), before it ceased reporting. Additionally, a pressure of 977.3 mbar (hPa; 28.86 inHg) was observed.[1] Deep convection steadily weakened and the hurricane's eye filled as the winds decreased.[14]
Increasing wind shear accelerated the rate of weakening, causing Blanca's mid- and low-level circulation centers to decouple.[15] By 18:00 UTC on June 7, the hurricane degraded to a tropical storm. Around 10:30 UTC on June 8, Blanca madelandfall overIsla Santa Margarita off the coast ofBaja California Sur before striking the mainland, near Puerto Argudin, at 11:15 UTC. This marked the earliest known landfall in the state, and peninsula, on record during a calendar year.[1] It surpassed the previous earliest—Tropical Storm Calvin on July 8, 1993—by a month.[10] Turning back to the northwest, the system briefly emerged back over the Pacific Ocean before weakening to a tropical depression. Blanca made its third and final landfall near El Patrocinio around 20:30 UTC.[1] With deep convection no longer present,[16] the depression degraded into a remnant low early on June 9 over the central Baja California peninsula before dissipating hours later.[1]
On June 3, precautionary alerts were raised across the southernBaja California Peninsula and much of Western Mexico, due to potential impacts from the hurricane.[17] Two days later, theGovernment of Mexico issued atropical storm watch for parts ofBaja California Sur before upgrading it to awarning on June 6. Warnings ultimately extended northward toPunta Abreojos. Ahurricane watch was temporarily in place; however, Blanca's abrupt weakening on June 7 prompted its discontinuation.[1] All schools were closed in Baja California Sur on June 8.[18] A collective 3,300 troops from the Mexican Army and Navy were deployed to Baja California Sur to ensure the safety of residents.[19] Under the threat of 5 m (16 ft) waves, the port of Los Cabos suspended operations.[20] WithinSonora, all schools in theEmpalme,Guaymas, andHermosillo municipalities were canceled for June 8.[21]
Waves up to 5 m (16 ft) damaged coastal installations inPuerto Vallarta,Jalisco.[22] A surfer was pulled out byrip currents near Villa Obregón and required rescue; however, the rescuer was also overcome and both drowned. Two fishermen ignored warnings to remain at port and died amid rough seas from the hurricane.[23] Striking Baja California Sur on June 8, Blanca brought tropical storm-force winds and heavy rain to the region. The highest sustained winds were observed atCabo San Lucas International Airport, reaching 46 mph (74 km/h) while gusts were measured at 52 mph (84 km/h) inSan Juanico.[1] Across the state, high winds downed power lines and left 104,106 residents without electricity. However, around 90 percent of the outages were fixed within 12 hours of the storm.[24] The winds also broke a few windows.[25]Sinaloa experienced similar effects, with strong winds downing many trees and tearing apart billboards, primarily inLos Mochis andGuasave.[26]
The remnants of Blanca, aided by an unusually late-season coastal low, later brought several days of scattered thunderstorms to theSouthwestern United States.[27] Effects in California were primarily concentrated across theMojave Desert and southernGreat Basin.[28][29] Daily rainfall records were broken in several areas, though accumulations were generally less than 1 in (25 mm).[29]Maricopa andTaft received 1.5 in (38 mm) of rain in 30 minutes, triggeringflash flooding that stranded vehicles and prompted the temporary closure ofState Route 166.[30] Flooding and mud flows covered parts ofState Route 190 inInyo County, resulting in an accident that injured two people.[28] Thunderstorm winds downed several trees, two of which fell on mobile homes.[31][32]Hail up to 1 in (2.5 cm) in diameter was observed inFord City.[33] Some flooding took place inSanta Barbara County.[34] Damage across the state amounted to $68,000.[35]
Record rainfall was observed in parts of Arizona, withYuma recording measurable precipitation for only the seventeenth time in June since records began in 1876. Rainfall amounted to 0.31 in (7.9 mm) in the city, and 0.21 in (5.3 mm) fell inTucson.[36] In Six Mile Canyon in Nevada, near the border ofLyon andStorey counties, 1.13 in (29 mm) of rain fell in an hour, resulting in flash flooding. Damage was primarily to landscaping with minor effects to homes.[37] The normally dry Pine Nut Creek inDresslerville rose 4 to 5 ft (1.2 to 1.5 m) in a short period of time, inundating nine homes and covering low water crossings.[38] Multiple roads acrossEsmeralda,Eureka, andLander counties were subjected to flooding.[39] Damage across Nevada was $46,000.[40]
Following above-average rainfall since April, renewed precipitation inNew Mexico led to flash flooding. Roads were washed away nearConchas Dam and minor flooding took place nearPojoaque.[41] A strong thunderstorm over theNavajo Nation in New Mexico spawned a briefEF0tornado nearNapi Headquarters.[42] Hail up to 1.75 in (4.4 cm) in diameter was observed and rainfall caused theAnimas River to overflow.[43] Damage in the state reached $20,000.[44] Flash flooding also took place inUtah, including along theParia River; astream gauge observed a peakflow of 1,160 ft3 (32.8 m3) per second.[45] A peak wind gust of 70 mph (110 km/h) was observed onFlattop Mountain inEmery County.[46]
Tropical cyclones of the2015 Pacific hurricane season | ||
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